SwRI has developed a new modular steel buttress dam system that will help resolve energy storage issues hindering the integration of renewable resources into the energy mix. Prefabricated structural members are ten feet high and ten to forty feet long so they can be trucked to the site using standard or low-boy flatbed trailers via the interstate highway system. Structural elements are assembled on-site using common heavy construction equipment to erect the buttress framework, whose face is subsequently clad with cylindrically curved steel plates.